Denial-of-service attacks (DoS) - Types And Preventions A Complete Guide

Last updated: July 17, 2023 Reading time: 5 minutes
Denial-Of-Service Attacks

Denial-of-service attacks (DoS) are a common way for hackers to take down websites, but they can also be used more subtly to gain access to networks or steal information.

Statistics revealed that in 2020, the number of attacks will increase by 60% and is likely to result from an increasing number of hackers and an increasingly connected cyber environment.

In this article, we’ll look at what is DoS, how they work, and how you can protect yourself against them.

What is a DoS Attack

A denial of service attack (DoS attack) is a type of cyberattack where the attacker tries to make a machine or network unavailable to its intended users. There are many ways to launch a DoS attack, but one common way is to flood the target with traffic from multiple sources so that it can’t handle all the requests and becomes unavailable.

In a typical DoS, the attacker will send many requests to the target machine or network. This can be done by flooding the target with traffic from multiple sources or using tools that automatically generate massive amounts of traffic. The goal is to overwhelm the target so it can’t handle all the requests and becomes unavailable.

(DDoS) Depth Analysis Of Working

In a distributed denial-of-service attack (DDoS), the attacker uses a botnet – a network of computers infected with malicious software – to send the requests. These computers are often called zombies and can remain infected without their owner’s knowledge.

The volume of traffic sent to the target during a DoS attack is usually much greater than the traffic the target would typically receive. The target might be a specific computer, such as a server hosting a website or an email server, or an entire network.

A DoS attack can also be used to mask another attack. The volume of traffic sent during a DoS attack is so high that it might be hard for the target to determine if there’s also an intrusion or if the traffic is just part of the attack.

DoS attacks are usually not meant to destroy data. Instead, they’re often used to gain unauthorized access to a network or computer.

How To Prevent Such Attacks?

There are several ways to protect yourself against DoS attacks. The most effective way is to use a firewall to block traffic from unauthorized sources. You can also use intrusion detection systems (IDS) to detect and prevent attacks.

You can also take steps to reduce the amount of traffic your target machine or network receives. For example, you can use caching to store popular content locally so that it doesn’t have to be requested from the server every time. You can also use load balancing to distribute the load across multiple servers.

In addition, you can monitor your environment to detect changes. For example, if an employee starts receiving many spam messages, that might indicate that the employee’s machine has been compromised and is being used to send spam. Or if you’re expecting a small amount of traffic at certain times of day but notice that it’s much more extensive than usual, that might indicate an attempted attack.

Types of DoS Attacks

There are several different types of DoS. Some of the most common types include:

  • Flooding: This is the most common type of DoS attack. The attacker sends many requests to the target machine or network, which overwhelms it and causes it to become unavailable.
  • Ping of death: This attack exploits a TCP/IP protocol vulnerability, allowing a malicious user to send huge packets to a target machine. These packets can crash the target machine or cause it to become unavailable.
  • SYN flood: This attack takes advantage of a vulnerability in establishing TCP connections. The attacker sends SYN packets to the target machine, which ties up resources as the target tries to respond to them all.
  • Smurf: This attack uses a flood that sends requests from zombie computers to a network’s broadcast address. The goal is for the zombies to respond and effectively amplify the attack.
  • Land: This attack overwhelms a target server with SYN packets sent from every zombie computer on a botnet.
  • Fraggle: This denial of service attack sends messages from the zombie computers to the broadcast address for a UDP service. It’s similar to a Smurf attack but uses UDP rather than TCP.
  • Ping flood: This DoS attack sends a ping from each zombie system to the targeted server.
  • Teardrop: This type of DoS attack exploits a vulnerability in older versions of Windows that allows an attacker to send malformed packets.
  • Zero-day: This attack uses malware that exploits a vulnerability that’s not yet been patched.
  • Evil twin: A wireless access point pretends to be a known network and tricks users into connecting. It then exploits the connection’s vulnerabilities to control the victim’s machine.
  • Domain name kiting: This attack overloads DNS servers by creating many requests for nonexistent names.
  • Email bombing: This type of attack uses automated programs to send many emails, overwhelming the target’s system and causing it to become unavailable.
  • Phishing: This attack damages a machine or network device so that it no longer works properly.
  • Distributed denial of service (DDoS): This attack uses multiple systems, all under the attacker’s control, to flood the target with requests.
  • Smurfing: This attack is similar to spam bombing, except it uses large groups of zombies rather than just one.

These are the most common DDoS attacks that you’ll encounter. The main thing to remember is that the goal of a DoS is to disrupt normal operations, either by disabling services or by overwhelming a machine or system.


Hope you now have a better understanding of what denial of service attacks are and how to protect yourself against them. If you have any questions, please post a comment below.

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About the Author

Rebecca James is an IT consultant with forward thinking approach toward developing IT infrastructures of SMEs. She writes to engage with individuals and raise awareness of digital security, privacy, and better IT infrastructure.

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